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Worcester Bosch Greenstar 4000 boiler review

Worcester Bosch 4000 Boiler Review

Worcester Bosch 4000 review – The Greenstar 4000 is ready to take the boiler industry by storm.

This Worcester 4000 review will give you everything you need to know about the UK’s most installed boiler, launched in 2021, and hydrogen ready.

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The Worcester 4000 comes with a really long warranty of up to 10-years (12-years if you buy from Boiler Central here) and have numerous Which? Best Buy awards to their name.

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Worcester Bosch Greenstar 4000 boiler review

In this Worcester 4000 review, you will find out everything you need to know about this brand new, mid-range boiler that is a revamped version of the most installed boiler in the UK, the Worcester Bosch Greenstar i boiler.

It was mid-May 2021 when Worcester released the Greenstar 4000 and we left this boiler review a good month to get an idea of how good they actually are since our trusted boiler partners install literally hundreds per day. Feedback is everything.

Worcester Bosch Greenstar 4000 boiler review Compare Boiler Quotes

The Worcester Bosch 30i combi is replaced by the Worcester 4000 combi and the system boilers range is replacing the Greenstar i system boilers range. See if these hit our best combi boiler list.

This new boiler range is aimed mid-range in the Worcester line up with the 2000 series their budget model and the 8000 series is the range-topping, full works.

This 4000 range, for combi boilers, comes in 25kW and 30kW versions just like the old Greenstar i range. The cost of a new boiler installation is very slightly higher but probably because it’s a new range completely.

Did you know that you can get a market-leading 12-year warranty with Boiler Central?

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Top features of the Worcester Bosch 4000 boiler reviewed

  • Really long warranties (10 years standard, 12-years with mavericks Boiler Central)
  • Perfect for small and medium size homes
  • Available in 25kW or 30kW for flexiblity
  • Priced competitively around £1,940 for a combi swap
  • ErP rating 94%: A-rated
  • Dimensions H 710 x W 400 x D 310
  • Can be used with smart thermostats / phones
  • Super reliable & trusty all-year round

Worcester Bosch 4000: Performance review

As briefly mentioned above this boiler range comes in two different power options for combi boilers:

  • 25kW
  • 30kW

The 25kW version is perfect for small and medium homes with up to 14 radiators, on average. Boasting a flow rate of 10.5 litres per minute which is more than enough for most homes.

The 30kW version is probably more suited for those with a little higher demand, with 16, maybe 17 radiators to give you a guide on the extra capabilities.

The 30kW 4000 really would be worthwhile if you have multiple showers or baths in use sometimes as it has a higher flow rate of 12.3 litres per minute to cope with a little more than the 25kW version.

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Worcester Bosch Greenstar 4000 system boiler

Although system boilers are gradually declining in popularity due to combi boilers being able to power higher flow rates every year, there is still a decent demand for a system boiler replacement in the UK.

What is a system boiler?

A system boiler is where you have a boiler and also a separate water tank, usually in the airing cupboard. Simple. We have a system boiler price guide if you need help choosing your boiler upgrade.

What sizes are the 4000 system boilers available in?

The system range of this new 4000 are below:

  • 12kW
  • 15kW
  • 18kW
  • 21kW
  • 24kW

How do you know which of the above are suitable for your home? The easiest way is to use our free online calculator here.

Worcester 4000 efficiency reviewed:

The 4000 range is really efficient. Boasting an A-Rated efficiency at 94% really is super-efficient.

This new model has all of the latest additions to make it as efficient as possible so your heating bills can be the lowest they’ve ever been.

Unless you’re heavy on the thermostat. Whilst on thermostats, you can link these to a nest or hive to get extra efficiency savings.

Best features and controls review of the 4000

Frost protection

Most Worcester Bosch boilers have frost protection and the 4000 range is no different. A real nice addition to this boiler for peace of mind.


Exactly what it says – eco mode will save you money on your bills and emit less carbon to the environment. Great news all-around!

A new look and an updated design

This superb mid-range 4000 boiler has a new look which is modern and really user friendly too. It features a lovely rounded design so if you can’t fit it in your kitchen cupboard, it’ll look fine on display.

Are the display and controls any good?

The display is a nice, easy to use push-button control on a black circle at the base of the boiler. It has smart connectivity so you can connect a Worcester EasyControl and power it remotely from your phone or tablet for example.

Side panels are easy to access for engineers

When you get your boiler serviced (you should annually to keep your warranty valid) the Gas Safe engineer will need to get ‘into’ your boiler.

Worcester have made it really easy with side panel access which means they can access what they need quick and easy.

Intelligent filling system (combi only)

As with the old Greenstar i that this model has been upgraded, the 4000 range has the same intelligent filling system.

In layman’s terms, this is basically a clever system that keeps the pressure of the boiler at the perfect level. If at any point the pressure drops then this clever system will just top it up, likewise if it drops it will alert you.

Greenstar 4000 control compatibility

The 4000 range is compatible with Worcester Bosch’ other controls such as:

  • EasyControls
  • Comfort+ RF
  • Comfort+ Stats RF
  • Comfort +
  • MT20

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Warranty review of the Greenstar 4000 boiler

The Greenstar 4000 comes with a 12-year warranty when purchased through Boiler Central. Click here to go there now and get a fixed online price.

But, if you go with anyone else, literally, no one else can offer you (included in the price) this exclusive extended warranty period. Terms apply but check with them first.

Other companies are lacking in the, erm, “warranty department” so you can expect to get a 7 to 10-year warranty with most providers.

You should really go with the longest warranty you can so if you do sell your home, it can add value by having a stress-free boiler warranty.

How much is the Worcester Bosch 4000 boiler?

You can get a fixed price online here quicker than you can by reading the below. Seriously.

Anyway, just in case you took the slow option, here is how much the 4000 will set you back:

For the 25kW and 30kW combi boiler Greenstar 4000 you can expect to pay around £1,850 to £1,995 with a horizontal flue, or add £200 for a vertical flue. This doesn’t include moving the boiler etc, literally just a boiler swap.

If you want to move your boiler’s location you can add £400 to £600 depending on where it’s going and if your converting from a system boiler (with tank) to a combi then add another £600(ish) to the cost.

Again you can use our free online calculator here to give you accurate pricing.

Worcester Bosch 4000 – Our review & conclusion

Simply put, this mid-range boiler from Worcester Bosch is probably going to be the most sold boiler in the UK over the coming 12-months.

It has everything. The only thing we think is even better is Boiler Central’s 12-year warranty – these guys are the mavericks of the boiler industry so if you are looking to buy the 4000 boilers, price one up with them here.

Other than that, we hope this review has been helpful in your decision on whether the new Greenstar 4000 is the boiler for you!

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What our customers think

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Would recommend

Stressed when needed a new boiler but easy process with affordable finance. New boiler installed within a few days with option for next day.

Paul Jones 5 Star on Trustpilot

We were very impressed

On the day, they came on time. Lovely people, they kept everything clean. Explained everything to me. No mess, kept me informed.

Anne Cross 5 Star on Trustpilot

Great Experience

Great experience - quick to arrange, easy to work with the very responsive online team and all installed faster than expected.

Ms Baxter 5 Star on Trustpilot

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